Sonographic Biometry of Fetal Interorbital Distance as a Predictor of Gestational Age in Enugu, Southeast Nigeria.

Objective: The objective of this study was to develop a sonographic technique for the measurement of fetal interorbital distance (IOD) for gestational age (GA) determination and to establish a normogram of IOD for the local population.

Methods: The fronto-transverse sonographic technique was established as a feasible and reproducible technique for IOD measurement. Two independent and experienced sonographers tested the technique and had a coefficient of variation of 17.64% and 19.72%, respectively, which is statistically insignificant. The established technique was used to measure the IOD of 320 fetuses from the 13 week to 40 week GA, while standard technique was used to measure biparietal diameter (BPD), head circumference (HC) and femur length (FL) of the fetuses. The data obtained were used to determine the regression equation GA = 6.24 + 4.89 IOD for the prediction of the gestational age.

Results: There was good correlation between IOD, BPD, HC and FL. The predicted normogram of IOD was compared with normogram of the Caucasian population. The result showed that there was no statistical difference between them (p < 0.05).

Conclusion: Results from the study suggest that the fronto-transverse technique is a feasible and reproducible technique for IOD measurement and the established normogram of IOD can be a veritable statistic for GA prediction in our locality.